Preliminary Study Of Antifungalmycin702Preventing And Curing Magnaporthe Grisea

Microbiology Laboratory of Jiangxi Agricultural University used solvent extraction method to get the crude antifungal active substance produced by Streptomyces702, and then used the column chromatography method to pure the crude antifungal active substance for getting antifungalmycin702. This issue researched the physiology and biochemical mechanism of antifungalmycin702on the induced resistance of Magnaporthe grisea, and it was hopeful to be exploited as a newful and high-performoance biologic bactericide, to prevent rice diseases.In order to explore the influence inhibitory effects of antifungalmycin702on Magnaporthe grisea106-2, this experiment took toxicity determination by mycelial growth rate method, watched colonial morphology, mycelium morphology, spore germination of Magnaporthe grisea by observation, analysed the influence of content of extracellular protein, extracellular polysaccharide, and enzymatic activity of cell wall-degrading enzymes of Magnaporthe grisea by spectrophotometry. The results show that the EC50and EC90of antifungalmycin702on hypha of Magnaporthe grisea were27.45and135.58μg/mL, and antifungalmycin702had strong inhibitory effect to the hyphe growth and spore germination, because it can effect the hyphe and spore form. Under EC50and EC90, content of extracellular protein, extracellular polysaccharide was less than control, so it proofed that antifungalmycin702can inhibit the generation of extracellular protein and extracellular polysaccharide of Magnaporthe grisea. Whether low or high concentration of antifungalmycin702(25μg/mL-100μg/mL), it can significantly reduce the enzyme activity of cell wall-degrading enzymes of Magnaporthe grisea (carboxymethyl cellulose, polygalacturonase and Pectin methylgalacturonase) respectively.Through resistance effects, spore germination rate, protein crosslinking and phenolic compounds detection, we found that the most efficient concentration of antifungalmycin702on rice to resist Magnaporthe grisea was80μg/mL, with control efficiency of39.07%. Also, antifungalmycin702had apparent inhibition to spore germination of Magnaporthe grisea, The spore germination rate of Magnaporthe grisea was28%inoculated96h later, reduced by66%than CK, it told us antifungalmycin702could decrease the number of spores into blades, so that it could reduce the risk of Magnaporthe grisea infecting rice.Research that antifungalmycin702controled the hypersensitive response, phenolic metabolism, and the activity of pathogenesis related protein of rice, demonstrated that antifungalmycin702application significantly increased activities of catalase (CAT), lipoxygenase (LOX) and peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonialyase (PAL), chitin cut the enzyme, chitin enzymes, and beta1,3-glucan enzyme, as well as the content of malondialdehyde (MDA). In the early stage of infection, antifungalmycin702bursted the content of reactive oxygen species in rice quickly, increased the level of membrane lipid peroxidation, and induced the hypersensitive response, so it could increase resistance of rice. Antifungalmycin702alleviated the oxidative damage during later periods of the rice Magnaporthe grisea interaction. And antifungalmycin702actively participated in metabolism of phenolics to accelerate accumulation of antimicrobial compounds. Also it improved chitinase and beta1,3-glucan activities to enhance resistance to Magnaporthe grisea.